Is it possible to mix with a Traktor Kontrol S2 mk3 and a Traktor Kontrol X1 mk2 in Traktor Pro 3? And if so, what is the configuration to be made in the Traktor Pro 3 software to be able to use both controllers at the same time!
Nothing needed, it should work out of the box.
Keep in mind the s2 can only control 2 decks. If you want to control deck C D with x1 that is possible, but you will have no volume or EQ control.
And if you control deck A and B with the x1 you share that with the s2.